Planetary gearing



Oct. 5, 1937. J. M. WALTER 2,095,207

PLANETARY GEARING Filed May 5, 1933 4 Sheets-Sheet l INVENTOR.

Oct. 5, 1937. J. M. WALTER PLANETARY GEARING Filed May 5, 1933 4 Sheets-Sheet 2 Oct. 5, 1937. J. M. WALTER PLANETARY GEARING Filed May 5, 1933 4 Sheets-Sheet 3 'IIIIIIIIII INVENTOR.

Oct. 5, 1937. J. M. WALTER PLANETARY GEARING Filed May 5, 1935 4 Sheets-Sheet 4 INVENTOR.

Patented Oct. 5, 1937 UNITED STATES PATENT OFFICE- 14 Claims.

My invention consists of a series of planetary gears, each meshing with a ring which is free to turn, or which may be prevented from turning. at will. The particular ring which is prevented from turning determines the speed of the driven member. My mechanism is compact, readily driven by an electric motor which may be so mounted as to form an integral part of the mechanism, and arranged so that the different speeds may be easily and quickly obtained. I also provide means for determining the different available output speeds, and for indicating the particular output speed in use. In order to illustrate the use of this invention, I have shown it as embodied in a milling head in which a driving motor, the speed changing mechanism and the milling spindle are embodied in a compact and self-contained unit.

In the drawings, Figure 1 is a front view of my invention; Figure 2 is a side view cut away to show a partial section on line A-A of Figure 1; Figure 3 is a plan view of the upper planet gear carrier with its planet gears; Figure 4 is a section through the upper planet gear carrier on line A--B in Figure 3, including the sliding clutches and clutch gears; Figure 5 is a front view of the pinion, shaft, worm gear, and worm, and a portion of the quill with the case removed, to illustrate the axial feed mechanism; Figure 6 is a vertical section through the worm and worm wheel of the axial feed mechanism; Figure '7 is a section through the spindle, lower planetary gear set and the quill; Figure 8 is a vertical section through the clutch shifting mechanism at the top of the motor, the section being taken through the axis of one of the clutch shifting shafts; Figure 9 is a horizontal section through the clutch shifting shafts; Figure 10 is a front view of the speed indicator; Figure 11 is a vertical section through the speed indicator on line A-A in Figure 1; Figure 12 is a front view of the outer sliding plate; Figure 13 is a front view illustrating the speed indicator with openings instead of notches, in the cover, and openings in the outer sliding plate, instead of indicating triangles; Fig ure 14 is a section through the sliding cylinder for interlocking the clutches and speed indicator taken on line A--BC in Figure 9, and Figure 15 is a front view of the outer sliding plate when provided with three openings, instead of three pairs of triangles and a continuous slot.

In order to simplify the description of the mechanism, it will be assumed throughout the description that the mechanism stands vertically as shown in Figure 1, although the mechanism may be inclined to any desired angle.

In the drawings, I. is a cast iron body or case in which is enclosed the greater part of the mechanism; 2 is a motor frame which, for the sake 5 of lightness, I prefer to make of aluminum. 2 is concentric with and fast to the top of body I. Pressed into the motor frame is stator 3 and revolving within this stator is rotor 4. In order to make the motor as compact as possible, it is prefl0 erable that the .stator and rotor be those of a polyphase induction motor, although the stationary part of any other type of motor can be substituted for the stator and the rotating part of the motor substituted for the rotor. Rotor .15 l is keyed to a hollow shaft 5. This shaft is supported by bearing 6 which I prefer to make a duplex ball bearing, and bearing 1 which may be of any suitable type. Bearing 6 is located in member 8 which serves the purpose of the end bell" of a motor and also serves to support other mechanism to be described later. Bearing 1 is supported in the lower part of frame 2. Below bearing 1 and fast to the shaft 5 is sun gear 9, which I prefer to cut integral with the shaft.

The upper part of body i is bored out, and within it are four concentric internal or ring gears l0, ll, l2 and I3. These gears are normally free to revolve in the bore of the body i but are provided on their exterior surfaces with holes or notches by means of which they can be prevented from revolving when so desired.

Concentric with shaft 5 is planet plate It having an extended hub l4--a. Planet plate i4 revolves on bearing l5, which is at its upper end and co-acts between the lower end of the shaft 5 and the planet plate It, and hearing it, which is at the lower end of hub i4a and co-acts between this hub and a second planet gear carrier to be described later.

In planet plate H are pressed three studs l1, equally spaced on the same radius, the center of this radius being concentric with shaft 5. On these studs are rotatably mounted three planet pinions i8, each of which meshes with gear 9 and the teeth out on the internal surface of ring gear i0. It will thus appear that when shaft 5 is rotated by the motor, and resistance is offered to the rotation of planet plate l4, ring gear [0 will be caused to rotate. If, however, ring gear I0 is prevented from rotating, planet plate It will be caused to rotate against the resistance applied to it, whenever the motor rotates.

on planet plate It and equally spaced on a different radius from the first, but concentric therewith, are three studs i3, on each of which is rotatably mounted a compound gear 20 consisting of a gear 20-4 meshing with gear 9 and internal ring gear II, and pinion 2||-b meshing with the internal ring gear l2. The planet plate with its attached studs constitutes what may be termed a planet gear carrier. The planet gear carrier with its associated planet gears and pinions and ring gears, constitutes what may be termed a planetary gear set. If ring gear ill be allowed to rotate freely and ring gear I i be held fast, the motor will drive planet plate l4 by means of gear 20-4. Since gear 20-41 is larger than pinion i8 and ring gear II has a larger pitch diameter than ring gear Ill, the planet plate will be driven at a slower speed than it would if ring gear i0 were held fast and ring gear allowed to revolve.

Theteeth of pinion 2||--b mesh with the teeth of ring gear i2. If ring gears l0 and H are allowed to revolve and ring gear i2 is held fast, planet plate l4 will be forced to revolve, but since the planet gears are now compounded, the rate of revolution of the plate will be still slower than if ring gear H were held fast and ring gear l2 allowed to revolve.

Slidably splined to the upper end of hub |4--a is clutch 2| while slidably splined to the lower end of this hub'is clutch 22. On this hub are rotatably mounted clutch gears 23 and 24, the clutch teeth of gear 23 being adapted to engage clutch 2| while the clutch teeth of gear 24 are adapted to engage clutch 22. planet plate I4 is planet plate 25 which also has an extended hub 25-a. At the upper end of this hub is bearing 25 and at the lower end is bearing 21. These two bearingsare mounted in member 28 which is bolted to body and is concentric with the motor, its shaft and the two planet gear carriers. Member 28 is in form a flange having a downwardly extending hollow cylinder which supports bearing 21. Mounted on planet plate 25 and equidistant on the same radius are three studs 23. On each stud is rotatably mounted a compound planet gear 30 consisting of gear 30-41. which meshes with gear 24 and pinion 30-17 which meshes with gear 23. Pinion 3|l-b also meshes with'ring gear i3.

It will be apparent from this construction that if ring gear |3 be allowed to rotate and clutches 2| and 22 engage clutch gears 23 and 24, planet plate 25 will be caused to rotate at the same speed as planet plate l4. In other words, the lower planet carrier and its associated ring gear i3, revolve as a unit with the sun gears. If clutch 2| is engaged and clutch 22 disengaged, clutch gear 23 will rotate planet pinion 30-12, and if ring gear |3 be held fast, planet plate 25 will rotate at a slower speed than planet plate l4. If, however, clutch 22 is engaged and clutch 2| is disengaged, clutch gear 24 will rotate planet gear 35-a, and due to the effect of the compounding, planet plate 25 will be caused to rotate at a still slower speed.

When ring gear I3 is held fast and clutch 2| is engaged, gear 24 will rotate freely on the hub |4--a, and if clutch 22 is engaged and clutch 2| disengaged, gear 23 will rotate freely on hub |4a.

It will thus be seen that since planet plate l4 can be driven at any one of three speeds by-a constant speed motor, and planet plate 25 can be driven at any one of three speeds by planet plate I4, planet plate 25 may be driven at any one of nine different speeds. The first three speeds are obtained with clutch 2| and 22 both engaged, by preventing ring gears III, II or l2 from revolv Below and concentric with The second three speeds are obtained if clutch 2| is engaged while clutch 22 is disengaged, and ring gear l3 and one ofthe three upper ring gears are prevented from revolving. The third set of three speeds are obtained if clutch 22 is engaged and clutch 2| disengaged, and ring gear l3 and one of the three upper ring gears are prevented from revolving.

In order to permit the assembly of planet plate 25 and planet gears 30, the upper ends of studs 29 are supported by a ring 3| which is bolted to planet plate 25 in the manner shown in the drawings, and forms part of the planet gear carrier. This makes itunnecessary to press the studs into the planet plate and by supporting the studs at both ends gives a more rigid construction.

The lower portion of body is bored to a smaller diameter than the upper portion, and in it slides cylindrical quill 32. In this quill are held fast a pair of taper roller bearings 33 whose inner races are fitted to hollow spindle 34. The

' bearings are preloaded by clamping the inner races between the flange which forms the outer end of the spindle, and the nut 34a which is threaded to the spindle. Spindle 34 is of the form usually used in milling machines except that its upper end is a sliding fit in the bore of the hub 25a of planet plate 25. At the lower end of hub 25-a are machined two standing keys 25-b which engage keyways 34-h cut on the exterior surface of spindle 34. Because of the extended hub 25-a of planet plate 25, the driving force which turns spindle 34 is applied as close as possible to the cutter, thus minimizing chatter.

On the exterior surface of quill 32 are cut rack teeth 32-a with which mesh the teeth of pinion 35. This pinion is cut integral with the shaft 35a, and on the end of this shaft is fastened worm wheel 36. Journaled in body is shaft 31 to which is afllxed worm 38 by the rotation of which pinion 35 is caused to revolve and thus raise or lower quill 32. Shaft 31 may be turned manually by means of a crank or may be turned by means of a feed mechanism in a manner described in pending application Number 633,008.

To the lower end of quill 32 is bolted flange 39 which holds the outer races of roller bearings 33 clamped in place between it and an internal shoulder formed in the bore of the quill. In order to insure that the outer races will be clamped before the inner races come together, ring 40 is placed between them to separate them. In order to prevent the quill from being turned by the friction of the roller bearings, a keyway is machined in its outer surface, and key 4| is fastened in a slot in case I, so that the quill can slide but not turn in the case. In order that the hub 25-a of planet plate 25 shall turn without changing its alignment because of loose bearings, bearings 26 and 21 are preloaded by nut 42 which is screwed onto the end of the hub 25-a.

The keys 25b which drive spindle 34, I make about three inches long. The remainder of the interior of hub 25-a up to the seat for bearing I6 is carefully bored to uniform diameter exactly concentric with the seats for the inner races of bearings 25 and 21. The upper three or four inches of the spindle 34 is carefully ground to fit the bore of hub 25-a so that the upper (or more properly the inner) end of the spindle will slide in the hub without perceptible shake. As the quill moves up and down, the spindle moves with it, sliding in the bore of the hub, and being aligned and guided thereby. The exterior surface of the spindle between the ground fit and the nut 34-a. is relieved slightly. I

It is customary to provide milling spindles with means for securing milling cutters, arbors, and holders for other forms of cutting tools, in a tapered bore in the outer end of the spindle. The most usual form of this means is a rod passing through a hole bored concentric in the spindle, and threaded at one end to engage the cutter, arbor, or holder, and at the other end to engage a nut for drawing the cutter securely into place. This necessitates that the inner end of the spindle be accessible. Since the inner end of the spindle in my invention is not accessible, I provide a rod 43, threaded at one end to engage the cutter, arbor or holder, and having near the middie of its length a shoulder 43-a which bears against a hardened washer 44 which is seated in a hole 34--c counterbored in the inner end of spindle 34. This rod extends through hub |4--a and hollow shaft to an accessible position where a head 43--b, similar in form to a nut, provides opportunity to turn it, and thus to draw the cutter snugly into the tapered hole. I make the diameter of the shoulder 43a such that the rod may be withdrawn when desired. The rod should be long enough so that head 43b is in an accessible position when the quill and spindle are run out to the limit of their travel. Such a rod I termed a draw bolt.

In order to shift clutches 2| and 22, radial holes are bored in each clutch. Into these holes in clutch 2| are pressed two pins 45 which project through two elongated holes routed in hub |4-a and engage two circular holes in sliding sleeve 46. In order to shift clutch 22, two pins 41 are pressed into clutch 22 and project through two elongated holes in hub |4a. and engage two holes in sliding sleeve 48. Sliding sleeve 48 is concentric with rod 43, and slightly larger in internal diameter than shoulder 43a Sliding sleeve 48 slides inside of sliding sleeve 46 and both sleeves project through the hollow shaft 5 to shifting mechanism located on member 8.

To the top of member 8 is bolted casting 49 which is bored so that the outer races of deep groove ball bearings 58 and 5| slide freely within it. The inner race of ball bearing 58 is clamped securely to sleeve 46 by nut 46-11. The inner race of ball bearing 5| is clamped securely to sleeve 52 by nut 52a. Sleeve 52 is threaded to the upper end of sliding sleeve 48. In casting 49 are formed two slots 49-41 and 49-1: in which are two sliding members 53 and 54. Sliding member 53 engages the outer race of ball bearing 58 while sliding member 54 engages the outer race of ball bearing 5|. Bored in casting 49 at an angle to one another and at right angles to the first bore are two holes 49-c and 49d. In hole 49c is shaft 55 having an eccentric projection 55a on the end thereof which engages a cross slot in sliding member 53. On the outer end of the shaft is crank 55b, having a handle 55-0 in which is a spring actuated poppet adapted to engage either one of two shallow conical depressions 49e and 49f on the surface of casting 49.

When crank 55b is in such a position that the poppet enters the upper depression 49-e, the eccentric projection 55a which engages with a slot in sliding member 53, holds the sliding member in its lower position, and thus sliding sleeve 46 is caused to hold clutch 2| in the engaged position. If, however, crank 55-4; is turned until the poppet engages the lower de pression 49-,f, sliding sleeve 48 will be raised and clutch 2| will be disengaged from the clutch gear 23 which it drives. Similarly, in hole 49-41 is a shaft 56 having an eccentric projection, adapted to engage a slot in sliding member 54.

It also is provided with a crank and poppet, the

per position, sliding sleeve 48 is raised, thus causing clutch 22 to engage and drive clutch gear 24. In the front of body I are bored five holes, |a being opposite ring gear l8, |-b opposite ring gear |-c opposite ring gear |2, l-d opposite the upper part of ring gear l3 and |-e opposite the lower part of ring gear l3. Below hole |e is bored a shallow depression of the same diameter as |-e. The center distances between |-a and b, |b and l-c, |d and l-e, and |e and |-f I make the same. For holes |-a, |'-b, and |c there is a poppet 51, the end of which is adapted to engage notches cut in the outer surface of ring gears IO, N and I2. If poppet 51 be placed in hole |-a and'ring gear |8' rotated until one of its notches is opposite the end of the poppet, spring 58 will force the poppet into the notch and prevent the ring gear from revolving. Similarly, by placing the poppet in hole |-b, ring gear may be prevented from revolving and by placing it in |c, ring gear |2 may be prevented from revolving.

For holes |--d and |-e and |-f there is a second poppet 59 similar to poppet 51. The end of poppet 59 is adapted to engage notches cut on the outer surface of ring gear I3. If poppet 59 be placed in the hole l-d or |e and ring gear |3 rotated until one of its notches is opposite the end of the poppet, spring 68 will force the poppet into the notch and prevent the ring gear from revolving. If, however, the end of the poppet is placed in the depression the ring gear will be free to revolve.

Concentric with poppet 51 is sleeve 6| which is firmly fixed by welding to sliding plate 62. Concentric with poppet 59 is sleeve 63 which is welded to sliding plate 64. Pinned to poppet 51 is handle 65 which slides over sleeve 6|, and pinned to poppet 59 is handle 66 which slides over sleeve 63. In order to move poppet 51, handle 65 is pulled out, compressing spring 58 and withdrawing the poppet from the hole in which it is placed. As soon as the poppet is free of the hole, it may be raised or loweredto enter either one of the other two holes, and so engage a different ring. In moving the poppet from one ring to another, sliding plate 62 moves up or down.

Similarly by pulling out handle 66, poppet 59 may be moved from one hole to another, and as it moves, sliding plate 64 moves up and down with it.

In order to indicate the various speeds obtained, I use the following method:

Covering sliding plates 62 and 64 is cover 61, in which is machined a long slot 81-a in which moves a plate 68 fastened to sliding plate 62. In it are also two slots 61b and 61c through which poppets 51 and 59 and their handles project. on plate 68 are marked or cast a series of nine numbers indicating the nine difierent speeds tion. 1

These notches exhibit portions of the face of sliding plate 64. On the face of plate 64 as shown in Figure 12, are marked three pairs of triangles, the upper pair of which appear through the upper pair of notches '61-d when plate 64 and poppet 59 are in their upper position, the second pair of which appear through the second pair of notches 51e when plate 64 is in its mid position, and the lower pair of which appear through the lower pair of notches 61-1 when plate 64 is in its lowest position.

It will be seen that for each of the three positions of poppet 59 a pair of triangles appear in one of the pairs of notches. Also, with poppet 51 in one of its three positions, one of three numbers appears in line with the pair of triangles. The number appearing opposite the pair of triangles thus indicates the normal speed of the.

spindle for the particular positions of the two poppets.

It is also possible to omit numbered plate 58 and instead of making continuous slots in cover and sliding plate 64, to substitute for them cover I61 as shown in Figure 13, and sliding plate I64 as shown in Figure 15, having three openings in cover I61, one opening in the place of each of the three pairs of notches, and to make three similar openings in plate I64, one opening in the place of each of the three pairs of triangles. The numbers indicating the nine speeds would then be marked on sliding plate 62 and one of the numbers would be visible through whichever opening in cover I61 coincided with an opening in sliding plate I64. For each position of the two poppets, the number appearing through the particular openings in plate I64 and cover I61 which would then coincide, would indicate the normal speed of the spindle. However, I prefer to use the method first described, since the entire list of spindle speeds is then in view at one time, and the number indicated, not being over-shadowed by the two openings, is easy to see.

It will be apparent that if poppet 59 engages ring I3 and both clutches are shiftedinto engagement, the mechanism will be locked and the motor stalled. The speed at which the spindle revolves is not determined by whether poppet 59 is in hole Id or Ie, but by which clutch is engaged. Accordingly, in order to prevent damage to the motor or the gearing and to make sure that the proper speed is indicated, I provide an interlocking mechanism so that when poppet 59 is in depression I], both clutches may be engaged; when it is in hole I-e only clutch 2I can be engaged and when it is in hole Id only clutch 22 can be engaged.

Pinned to the upper end of sliding plate 64 is a sliding cylinder 69 which slides in ahole 49-g in casting 49. On shaft 55 a fiat is milled opposite a hole drilled in casting 49 at right angles to both holes 49-0 and 49-9. On shaft 56 a similar fiat is milled opposite a hole which is drilled at right angles to both holes 49-d and 49-11. In these holes are cylindrical interlock pins 10 and 1i with flat ends and of such length that when they. touch the flats of the shafts 55 or 56, they also touch the outer surface of sliding cylinder 69. The fiats on the shafts 55 and 56 are at right angles to the axes of pins 15 and II when the cranks on the shafts are in their lower positions and the clutches, are disengaged. Sliding cylinder 69 has on it three flats 69-41, 69-1), and 69-c. When poppet 59 is in depression 'I-f, sliding cylinder 69 is in its lowest position and flats 69--a and 69-h come opposite the ends of interlock pins 10 and :II, permitting shafts 55 and 58 to be rotated so as to engage both clutches 2I and 22. If, however, it is attempted to raise poppet 59 with the clutches engaged, this will be impossible since the flat 69-4) is too short. If, however, shaft 56 be turned so as to disengage clutch 22, poppet 59 may be raised until it engages hole I-e and stops the rotation of ring gear I3. In raising the poppet, sliding plate 64 and sliding cylinder 69 are raised, pushing interlock pin 1I against the fiat on shaft 55.

If, however, it is then attempted to raise poppet 59 to its upper position, this will be impossible because the fiat 69-a against which pin 10 bears is not long enough to permit this. Before the poppet can be raised to its upper position, shaft 55 must be turned so as to disengage clutch 2i in order to permit interlock pin 10 to move aside till it touches the flat on'shaft 55. However, there is now a fiat 690 on sliding. cylinder 69 which permits interlock pin 1| to be shifted by rotating shaft 56 to engage clutch 22. It will be seen from this that both clutches cannot be engaged when poppet 51 is in hole Id or I6 and so prevents the ring I3 from turning. Also, if the poppet is in hole I-d, only clutch 22 can be engaged, while with the poppet in hole I-e, only clutch 2i can be engaged, so that if the spindle is running, it must be running at the speed indicated by the number opposite the triangles exhibited, or visible through the openings.

In order to support ring I3, three bronze shoes 12 are fastenedto planet plate 25. when the ring is prevented from rotating, its weight rests on the three shoes and the planet plate revolves under it. When the ring rotates, it is carried with the planet plate on these shoes. In order to support ring I2, a ball bearing consisting of a bronze ball retainer 13 in which are placed a number of steel balls, is used. The balls run on the upper surface of ring 3|, and support the lower surface of ringgear I2. A similar ball retainer 14 rests on the ring gear I2 and the balls support the ring gear I I. A similiar ball retainer 15 rests on ring gear II and the balls support ring gear III. By the use of these special ball bearings, friction between the surfaces of the rings is prevented. Since the loads are light and the balls are numerous, no special treatment is required for the surfaces over which the balls run, except that they must have a good, smooth finish.

In order to support clutch gear 24, there is put on the upper surface of planet plate 25 a hardened steel ring or washer 16 which supports the lower ends of the teeth of the clutch gear. Clutch gear 23 is supported on the top of clutch gear 24 by a second hardened steel washer 11 which is interposed between them.

I claim as my invention:

1. In a gear train, a planet gear carrier, a sun pinion for driving, a first ring gear normally free to revolve, a second ring gear of different pitch diameter from the first and also normally free to revolve, a third ring gear normally free to revolve, one or more first planet gears meshing with the first ring gear and the sun pinion, one or more second planet gears meshing with the second ring gear and the sun pinion, a planet pinion fast to each second planet gear so as to revolve therewith and to mesh with the third ring gear, and means for preventing the first, the second, or the third ring gear from revolving.

2. In a gear train, a hollow driving shaft, 9. first clutch gear free to revolve thereon, a second clutch gear of lesser pitch diameter free to revolve on the shaft, a first clutch slidably splined to the shaft and adapted to drive the first clutch gear, a second clutch gear slidably splined to the shaft and adapted to drive the second clutch gear, a planet gear carrier, a ring gear normally freeto revolve, one or more planet gears meshing with the second clutch gear, a planet pinion fast to each planet gear so as to revolve therewith and to mesh with both the first clutch gear and the ring gear, means for preventing the ring gear from revolving, a member slidable within the shaft for shifting the first clutch, and a member slidable within the shaft for shifting the second clutch.

3. In a machine tool, a spindle, a planet gear carrier rotatably mounted concentric therewith, slidably keyed thereto and adapted to guide the inner end thereof, and power driven gearing for driving the planet gear carrier at a plurality of speeds.

4. In a machine tool, a spindle, a first planetary gear set including a planet gear carrier rotatably mounted concentric with, slidably keyed to and internally bored so as to guide the inner end of the spindle, a second planetaty gear set rotatably mounted concentric with and adapted to drive the first planetary gear set, and power means for driving the second planetary gear set.

5. In combination, a spindle slidable axially and rotatably mounted near its outer end, a first planetary gear set including a planet gear carrier rotatably mounted concentric with, slidably keyed to, and internally bored so as to guide the inner end of the spindle, a second planetary gear set concentric with and adapted to drive the first planetary gear set, and an electric motor adapted to drive the planetary gear set.

6. In a machine tool, a spindle slidable axially, a first planetary gear set including a planet gear carrier rotatably' mounted concentric with and slidably keyed to the spindle and adapted to guide the inner end thereof, a second planetary gear set adapted to drive the first planetary gear set and concentric with the spindle, and an electric motor concentric with the spindle for driving the second planetary gear set.

7. In a machine tool, a spindle slidable axially, a first planetary gear set including a first ring gear normally free to revolve and a planet gear carrier rotatably mounted concentric with and slidably keyed to the spindle and adapted to guide the inner end thereof, a second planetary gear set including a plurality of ring gears normally free to revolve and a planet gear carrier concentric with the first planetary gear set and adapted to drive the planet gears thereof, means for preventing the first ring gear from revolving, means for preventing any one of the plurality of ring gears from revolving, and means for driving the second planetary gear set.

8. In a machine tool, a hollow spindle adapted to be moved axially, a planet gear carrier rotatably mounted concentric with the spindle, slidably keyed thereto, and internally bored so as'to guide the internal end thereof, a ring gear normally free to revolve and concentric with the planet gear carrier, a hollow power driven shaft concentric with the spindle, a first clutch gear rotatably mounted on the shaft, a second clutch gear of lesser pitch diameter rotatably mounted on the shaft, a first clutch slidably splined to the shaft and adapted to drive the first. clutch gear, a second clutch slidably splined to the shaft and adapted to drive the second clutch gear, one or more planetary gears each meshing with the second clutch gear, one or more planetary plnions, one fast to and concentric with each planetary gear and each meshing with both the first clutch gear and the ring gear, means for preventing the ring gear from revolving, means for shifting the first clutch and means for shifting the second clutch.

9. In combination in a speed changing device, a first speed changing means, a first movable member bearing indicating marks spaced apart and attached to and moving with the first speed changing means, a fixed member having openings equal in number to the indicating marks and so spaced so as to exhibit one of the indicating marks in accordance with the position of the first speed changing means, a second speed changing means, and'a second movable member attached to and moving with the second speed changing means and bearing numbers indicating the several available speeds so spaced that the speed normally obtained with each position of the first and second speed changing means appears opposite the indicatingmark exhibited.

10. In combination in a speed changing device,

a first speed changing means, a first movable member attached to and sliding with the first speed changing means and having openings therein spaced apart, a fixed member having an opening for each of the openings in the first movable member so spaced as to exhibit one of the openings in the first movable member in accordance with the position of the first speed changing means, a second speed changing means, and a second movable member attached to and sliding with the second speed changing means and bearing numbers indicating the several available speeds so spaced that the speed normally obtained with each position of the first and second speed changing means appears through the exhibited opening in the first movable member.

11. In a machine tool, a spindle adapted to be moved axially, a planet gear carrier rotatably mounted concentric with the spindle, slidably keyed thereto, and adapted to guide the inner end thereof, and power means for driving the' planet gear carrier.

12. In a mechanism, a motor having a hollow shaft, a hollow spindle coaxial therewith, plane- .tary gearing driven by the motor and comprising a first sun gear fast to the shaft of the motor, a plurality of coaxial ring gears normally free to revolve, means adapted to prevent the rotation sun gear, clutch means adapted to cause the second planet carrier and its associated ring gear to revolve as a unit with the second sun gear when the second ring gear is free, and means for driving the spindle by the second planet carrier.

13. In a. mechanism, a motor having a hollow shaft, a hollow spindle coaxial therewith, planetary gearing driven by the motor, and comprising a first sun gear fast to the shaft of the motor, a plurality of coaxial ring gears normally free to revolve, means adapted to prevent the rotation of any one of the ring gears, a plurality of planet gears meshing with the ring gears, a first planet carrier adapted to support the pinrality of planet gears, a second sun gear driven by the first planet carrier, a plurality of planet gears driven by the second sun gear, a ring gear meshing with planet gears driven by the second sun gear and normally free to revolve, means for preventing the latter ring gear from revolving, a second planet carrier adapted to support the planet gears driven by the second sun gear. clutch means adapted to cause the second planet carrier and the ring gear to revolve as a unit with the,

second sun gear when the second ring gear is free, and means for driving the spindle by the second planet carrier.

14. In a mechanism, a motor having a hollow shaft, a hollow spindle coaxial therewith, planetary gearing driven by the motor and adapted to drive the spindle at a plurality oi. speeds, the said planetary gearing having a hollow planet carrier coaxial with the spindle and the motor, and a draw bolt extending through the hollow motor shaft and the hollow planet carrier into the hollow spindle.

JOHN M. WALTER. 

